Define the equity, sampling and drawdown units
Chekhlov, Uryasev and Zabarankin define CDaR using the underwater curve. Their optimization formulation uses drawdown differences on uncompounded cumulative returns. Here we apply the same tail-average operation to relative drawdowns on a compounded account-equity path. Label that percentage convention explicitly; its values and portfolio-optimization properties should not be silently substituted for the original additive formulation.
- Use E0 as starting equity. At time t, running peak Pt = max(E0, E1, ..., Et), and relative drawdown Dt = 1 - Et/Pt. A new high has zero drawdown. With positive equity, these magnitudes lie from 0% to below 100%.
- The example uses one observation per trading-day close, after assumed costs and including open-position valuations. It has no deposits or withdrawals. Starting equity sets the initial peak but is not an extra observation in the eight-day distribution.
- For cash-flow-adjusted returns rt, a normalized equity index can be constructed as Et = E(t-1) × (1 + rt). A deposit or withdrawal must not be mistaken for investment performance.
- Absolute drawdown Pt - Et has currency units; dividing by Pt gives the percentage convention used here. Choose one measure, date range and valuation schedule for all strategies being compared.